The quality and safety of many temperature-sensitive products such as pharmaceuticals, food products, chemicals, and biological products can be adversely affected by improper temperature control during processing, distribution, and storage. As a result, there are many circumstances where it may be necessary to process, ship, and/or store temperature-sensitive products in a low-temperature environment.
To accommodate the need to maintain a low-temperature environment, a wide variety of insulated containers have been developed. Generally, these containers use different types of refrigeration and insulation materials to maintain a desired thermal environment within the container. To ensure that a desired thermal environment has been maintained in such containers, various temperature monitoring devices have been developed to be used in conjunction with the thermal containers. Time-Temperature Indicators (TTI) and electronic monitoring devices are examples of two devices that are commonly used for monitoring the temperature exposures of various products.
TTI devices generally use a change in physical appearance to indicate temperature exposure. TTIs typically use physical, chemical, electrochemical, enzymatic, or microbiological change that may be expressed as a visible response in the form of a mechanical deformation, color development, or color movement. The rate of change can be temperature dependent so that it increases at higher temperatures. As a result, the physical response may be used to give a cumulative indication of the temperature conditions to which the TTI has been exposed. Typically, these TTI devices are inexpensive and may be in the form of a label that can be attached or adhered to packages or objects. TTI devices generally need to be placed in the interior of the container in close proximity to the monitored product, and as a result, require the container to be opened in order to permit visualization of the TTI. However, in many circumstances it may be undesirable to open the container until it has reached its final destination and/or just prior to use. A further disadvantage of TTI devices is that the indicators may give false readings. False readings could result in the disposal or rejection of otherwise acceptable products.
Electronic monitoring devices are a second type of device that may be used to monitor temperature exposure. Electronic monitoring devices are typically small portable devices that include instruments and memory for measuring and storing temperature readings. Electronic monitoring devices, such as data loggers, can be used to monitor and record a variety of different environmental parameters. Data loggers are small, battery-powered devices that may be equipped with a microprocessor, sensors, and a memory for storing data. Data loggers may be programmed to take specific measurements at desired time intervals. Data loggers can be used to create a more complete and accurate picture of any changes in environmental conditions. Generally, the data logger must be placed in close proximity to the product being monitored in order to provide an accurate temperature measurement of the product. However, in many cases it may not be practical to place the data logger in the interior of the container. As a result, many conventional data loggers cannot be used to measure the interior temperature of the container. Accordingly, there still exists a need for an improved insulated container and method that can be used to measure the interior temperature of the insulated container.